Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$190.26	10.405%	$210.0566	$210.06	$210.05	$210.10
Purchase #2	$118.66	10.613%	$131.2534	$131.25	$131.25	$131.30
Purchase #3	$134.43	12.223%	$150.8614	$150.86	$150.85	$150.90
Purchase #4	$96.48	7.163%	$103.3909	$103.39	$103.40	$103.40
Purchase #5	$235.62	10.295%	$259.8771	$259.88	$259.90	$259.90
Purchase #6	$59.55	12.848%	$67.201	$67.20	$67.20	$67.20
Purchase #7	$90.54	13.392%	$102.6651	$102.67	$102.65	$102.70
7 purchase totals =	$925.54		$1,025.3055	$1,025.31	$1,025.30	$1,025.50